Bring in new IDL files and generated code. Update the script that syncs the idl files to deal with …

dart/sdk/lib/web_audio/dart2js/web_audio_dart2js.dart

 library dart.dom.web_audio;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:html';
 import 'dart:html_common';
 import 'dart:_js_helper' show Creates, Returns, convertDartClosureToJS;
 import 'dart:_foreign_helper' show JS;
 // DO NOT EDIT - unless you are editing documentation as per:
 // https://code.google.com/p/dart/wiki/ContributingHTMLDocumentation
@@ skipping 301 matching lines @@
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 
 @DocsEditable
 @DomName('AudioDestinationNode')
 class AudioDestinationNode extends AudioNode native "*AudioDestinationNode" {
 
-  @DomName('AudioDestinationNode.numberOfChannels')
+  @DomName('AudioDestinationNode.maxChannelCount')
   @DocsEditable
-  final int numberOfChannels;
+  final int maxChannelCount;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 
 @DocsEditable
 @DomName('AudioGain')
 class AudioGain extends AudioParam native "*AudioGain" {
 }
@@ skipping 543 matching lines @@
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 
 @DocsEditable
 @DomName('WaveTable')
 class WaveTable native "*WaveTable" {
 }